[release-20.0] bugfix: treat EXPLAIN like SELECT (#17054) (#17057)

Signed-off-by: Andres Taylor <andres@planetscale.com> Co-authored-by: Andrés Taylor <andres@planetscale.com>
vitessio · Oct 25, 2024 · 2043068 · 2043068
1 parent 6d2ef17
commit 2043068
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Showing 4 changed files with 31 additions and 12 deletions.
diff --git a/go/vt/vttablet/endtoend/queries_test.go b/go/vt/vttablet/endtoend/queries_test.go
@@ -121,6 +121,20 @@ var TestQueryCases = []framework.Testable{
 		},
 		RowsReturned: 1,
 	},
+	&framework.TestCase{
+		Name:  "explain with bindvars",
+		Query: "explain select :__vtudvp as `@p` from dual",
+		BindVars: map[string]*querypb.BindVariable{
+			"__vtudvp": sqltypes.Int64BindVariable(1),
+		},
+		Result: [][]string{
+			{"1", "SIMPLE", "", "", "", "", "", "", "", "", "", "No tables used"},
+		},
+		Rewritten: []string{
+			"explain select 1 as `@p` from dual",
+		},
+		RowsReturned: 1,
+	},
 	&framework.TestCase{
 		Name:  "limit",
 		Query: "select /* limit */ eid, id from vitess_a limit :a",

diff --git a/go/vt/vttablet/endtoend/transaction_test.go b/go/vt/vttablet/endtoend/transaction_test.go
@@ -256,7 +256,7 @@ func TestPrepareRollback(t *testing.T) {
 	err = client.Prepare("aa")
 	if err != nil {
 		client.RollbackPrepared("aa", 0)
-		t.Fatalf(err.Error())
+		t.Fatal(err.Error())
 	}
 	err = client.RollbackPrepared("aa", 0)
 	require.NoError(t, err)

diff --git a/go/vt/vttablet/tabletserver/planbuilder/plan.go b/go/vt/vttablet/tabletserver/planbuilder/plan.go
@@ -234,7 +234,9 @@ func Build(env *vtenv.Environment, statement sqlparser.Statement, tables map[str
 	case *sqlparser.Show:
 		plan, err = analyzeShow(stmt, dbName)
 	case *sqlparser.Analyze, sqlparser.Explain:
-		plan, err = &Plan{PlanID: PlanOtherRead}, nil
+		// Analyze and Explain are treated as read-only queries.
+		// We send down a string, and get a table result back.
+		plan = &Plan{PlanID: PlanSelect, FullQuery: GenerateFullQuery(stmt)}
 	case *sqlparser.OtherAdmin:
 		plan, err = &Plan{PlanID: PlanOtherAdmin}, nil
 	case *sqlparser.Savepoint:

diff --git a/go/vt/vttablet/tabletserver/planbuilder/testdata/exec_cases.txt b/go/vt/vttablet/tabletserver/planbuilder/testdata/exec_cases.txt
@@ -763,14 +763,15 @@ options:PassthroughDMLs
 # analyze
 "analyze table a"
 {
-  "PlanID": "OtherRead",
+  "PlanID": "Select",
   "TableName": "",
   "Permissions": [
-      {
-        "TableName": "a",
-        "Role": 1
-      }
-  ]
+    {
+      "TableName": "a",
+      "Role": 1
+    }
+  ],
+  "FullQuery": "analyze table a"
 }
 
 # show
@@ -783,15 +784,17 @@ options:PassthroughDMLs
 # describe
 "describe a"
 {
-  "PlanID": "OtherRead",
-  "TableName": ""
+  "PlanID": "Select",
+  "TableName": "",
+  "FullQuery": "explain a"
 }
 
 # explain
 "explain a"
 {
-  "PlanID": "OtherRead",
-  "TableName": ""
+  "PlanID": "Select",
+  "TableName": "",
+  "FullQuery": "explain a"
 }
 
 # repair